How to install the antivirus for a Aspire one laptop?

Use the help link within the app.
Open Bitdefender and click on the help button at the top of your screen.

Use security tool like Firewal and Antivirus , change your laptop password your wifi/access point wifi password and speak to an expert preferably contact the tech support of your computer manufacturer your ISP

There are two really good virus removers for your Acer Bitdefender Antivirus Plus (around $30.00) and Panda Antivirus Pro (around $40.00) you can find out where to get them at toptenreviews.com, I have used the bitdefender and it is excellent. Hope this was helpful.

If you do not have sufficient anti virus / spyware software then you most likely have a virus.
Clarify with what antivirus you have installed if any...
If you don't have any then I would suggest buying one of the following
Bit Defender Internet Security or Antivirus Pro http://www.bitdefender.com/2011/en/internetsecurity2011/?gclid=CLjrkuuU-6kCFQQCbAodJX-fZg
Webroot Internet Security or Antivirus with spysweeper http://www.webroot.com/En_US/consumer.html
or Kaspersky Internet Security http://usa.kaspersky.com/store/all-products?c_id=GOO1673628
Once installed make sure to update the software and run a full scan If you are unable to update the software Reboot the computer and press F8 until you get a menu Select "Safemode with networking" You should now be able to update the software and run a full scan

Hi,
As your question is incomplete I am giving you a link where you can get the general instructions to clean the PC from virus infections.


http://www.ehow.com/how_113706_clean-virus-infected.html

I give you the solve. 1st format the OS drive. Then install the OS again, after that install Bitdefender Security. After installation of bitdefender restart the laptop and run for drivers installation. Remember first bitdifender then driver. Becouse Bitdiffender block all driver's for security.Hope you understand. Pease ask me if you want more help.Thanks.

You can attempt to clean the virus. There are a variety of tools available to help you do this.Combofix will help you get started it will automatically clean part or all of the malware automatically. Just download and run it.
http://www.combofix.org/download.php
After its done try running your anti-virus to scan for viruses. If the virus is blocking it, start your computer in safemode and try scanning again. If it doesn't work too you can use the windows recovery console to try and restore your system. More information can be found at the link below
http://support.microsoft.com/kb/307654

Let me know if you need more help,
Sai.